This application is a continuation in part of co-pending U.S. application Ser. No. 09/757,166, filed on Jan. 10, 2001, now abandoned which claims priority from the U.S. Provisional Patent Application No. 60,242,958 to Lingel et al. filed on Oct. 24, 2000.
This invention relates generally to circulators that can be implemented in surface mount packages and particularly to a circulator that can be fabricated in a package whose shape can be selected to conform to the requirements of a microwave circuit whose arrangement is affected by other constraints. In the production of microwave circuits the use of components that are mounted on tape reels greatly increases the speed and efficiency of production, for example in so-called pick and place automated production line.
A circulator is a device having several ports for electrical communication with other devices in which energy entering the device through one of the ports is transmitted to a port that is adjacent to the first port. Circulators have been used for many years in coupling microwave energy transmitted in waveguides. There are several circulators known in the prior art that utilize stripline microwave transmission lines. For example, U.S. Pat. No. 4,276,522 to Coerver describes a circulator in a stripline microwave transmission line circuit Additionally, there are known various methods of forming stripline circuit components. Most notably, U.S. Pat. No. 4,821,007 describes a method of manufacturing a strip line circuit component that has particular advantages in packaging components to be soldered directly to conventional circuit boards. The assignee of the present application is also the assignee of U.S. Pat. No. 4,821,007 which is incorporated herein by reference.
To date, there has not been a suitable and cost-effective circulator for use in automated manufacturing, particularly for use in reflow operations. Indeed, there is a need for a circulator that can be packaged in component form and soldered directly to conventional circuit boards. Preferably, the component form is one that allows for supplying the components to the end-user in a tape and reel thereby allowing for quick and efficient production of the circuit boards. It is also desirable to provide a circulator package that can be soldered to circuit board in such fashion to allow for visual inspection of the solder joints.